Fuel injection systems in modern vehicles comprise a fuel sending unit mounted on the gas tank of the vehicle and functioning as a connection between the fuel pump and fuel gauge inside the tank, and the fuel piping system to the engine of the vehicle. The outlet tubes of a sending unit comprise swaged tube ends cooperating with mating mechanical fittings and defining with the mechanical fittings releasable connections in the fuel lines. Similar releasable connections are often found at other locations along a fuel piping system and on power steering units. These tubes, as supplied by the original manufacturer are normally made of steel and are prone to corrosion for being located under the vehicle and for being exposed to all driving conditions.
A sending unit with corroded outlet tubes is normally replaced by a new one at the expenses of the owner of the vehicle. The primary reason for not repairing sending units, which would save substantial amounts of money in repair costs, is believed to be because there are no tool available commercially to precisely manufacture the swaged tube ends using common garage equipment.
The swaging of a metal tube, and forming a bead on the end of the tube are difficult to control. It has been experienced that the tube tends to pucker, crumble or otherwise take unwanted deformation. The material of the tube may even crack or split.
Some types of bead-forming tools of the prior art have a pilot stem to enter the tube and to guide a die block onto the tube for maintaining the symmetry of the bead about the tube's axis. However, sending units of most North-American-made vehicles have tube ends formed with a bead and a reduction in tube diameter adjacent to the bead. In these cases, the use of a pilot member is useless for forming tube ends that are concentric with the axis of the tube.
It is believed that there are at least two requirements that must be taken into consideration for properly swaging a tube. The first one being that the swaging die must remain in perfect alignment with the axis of the tube, and the second being that the length of tube entering the swaging die must be precisely controlled. It is further believed that these two requirements must be found in a single tool in order to form tube ends that will not leak, that will easily engage into a mechanical fitting, and that will remain engaged in the mechanical fitting. It is believed that in general, the manual flaring tools of the prior art are lacking at least one and most often both of these structural requirements.
In a first example of the tools of the prior art, U.S. Pat. No. 2,483,982 issued on Oct. 4, 1949 to Joseph N. Paquin, discloses a manual flaring tool having a pair of elongated tube holder blocks. Each block is formed with a series of semicircular recesses which cooperate to form tube gripping bores when the blocks are brought together and clamped about a tube. A flaring head is movable along the tube holder blocks into a pair of guide channels respectively fastened to each of the tube holder blocks. A series of index marks are provided on the channel members, which marks are aligned with the axis of the corresponding tube recesses. A precise alignment of the flaring head over a tube to be flared is obtained by aligning an index mark on the flaring head with a selected index mark on one of the channel members. When this is done, the tube is readily flared by rotation of a flaring tool operator mounted through the flaring head.
In a second example, U.S. Pat. No. 3,415,100 issued on Dec. 10, 1968 to Frank J. Britts, discloses a hand tool for swaging and forming a bead near the end of a tube. The tool includes an inverted U-shaped frame portion having a pair of legs each provided with a notch for respective engagement with opposing side walls of a pair of tube clamping blocks. The blocks are provided with semicircular tube holding recesses to accommodate tubes of various diameters. The base of the U-shaped frame is provided with a threaded aperture and a threaded shaft is mounted therein. The shaft has a head and a handle adapted to rotate the shaft to move the shaft up or down. A die body is connected to the shaft and has a die opening to form the tube. A pair of slots are provided along the die body. These slots are engaged onto the legs of the U-shaped frame, and are used for guiding the die body relative to the tube during the tube forming process.
Another example of a manual swaging tool for forming a bead on a tube is disclosed in U.S. Pat. No. 3,575,033 issued on Apr. 13, 1971, to Howard F. Meyer, Jr. This tool comprises conventional flaring yoke and bar assembly similar to the previously described tools. The die member used in this invention has a projecting guide pin that fits into the tube end and extends beyond the desired location of the bead to be formed. The projecting guide pin keeps the die member aligned with the tube during the bead forming process.
In yet another example of a manual tool for forming a bead onto a tube is disclosed in U.S. Pat. No. 4,754,634, issued on Jul. 5, 1988 to Sakae Murata. In this device, the die member is guided between the legs of a U-shaped yoke and by a short pin projecting from the forming end of the die block and extending into the tube to be formed.
Other tube forming equipment are disclosed in several U.S. Patents and in particular in:
U.S. Pat. No. 4,606,214, issued on Aug. 19, 1986 to Takeshi Miyazaki; PA0 U.S. Pat. No. 4,980,961, issued on Jan. 1, 1991 to Maurice L. Caudill; PA0 U.S. Pat. No. 5,487,294, issued on Jan. 30, 1996 to Horst U. Petersen. PA0 A) enclosing a tube in a pair of clamping blocks; PA0 B) positioning the tube in the clamping blocks and exposing a tube end portion of the tube beyond a surface of the clamping blocks while gauging the length of the tube end portion according to an ideal dimension of a comparative-type standard; PA0 C) forcibly retaining the clamping blocks in a vise; PA0 D) fittingly enclosing the clamping blocks inside an annular collar; PA0 E) fittingly enclosing a hollow bushing inside the annular collar, and against the surface of the clamping blocks; PA0 F) fittingly inserting the punch bar inside the hollow bushing while guiding the punch bar along an engagement dimension in the hollow bushing which is at least as long as the length of the tube end portion; and PA0 G) striking the punch bar with a hammer for working the first die cavity onto the tube end for forming a fitting on the tube end.
These later examples of tools of the prior art are also characterized by the fact that each has a pilot stem entering into the tube for controlling the deformation of the tube. It will be appreciated that the flared tube ends formable using a tool having a pilot stem are limited to those where the inside diameter of the tube beyond the bead is similar to the nominal inside diameter of the tube.
In view of the foregoing, it is believed that there is a significant market demand for tool kits capable of reliably swaging tube ends and providing for the replacement of outlet tubes on fuel sending units, fuel lines and power steering units, using common hand tools and equipment normally found in mechanical workshops.